21500587 has 2 divisors, whose sum is σ = 21500588. Its totient is φ = 21500586.

The previous prime is 21500543. The next prime is 21500593. The reversal of 21500587 is 78500512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21500587 - 2⁷ = 21500459 is a prime.

It is a plaindrome in base 11.

It is not a weakly prime, because it can be changed into another prime (21500527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750293 + 10750294.

It is an arithmetic number, because the mean of its divisors is an integer number (10750294).

Almost surely, 2^21500587 is an apocalyptic number.

21500587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500587 is an equidigital number, since it uses as much as digits as its factorization.

21500587 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2800, while the sum is 28.

The square root of 21500587 is about 4636.8725451537. The cubic root of 21500587 is about 278.0674189091.

The spelling of 21500587 in words is "twenty-one million, five hundred thousand, five hundred eighty-seven".